Process for the preparation of ivacaftor

ABSTRACT

The present invention provides processes for the preparation of ivacaftor using novel intermediates and a process for its preparation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of and claims the benefitof the filing date and disclosure of U.S. Application Ser. No.15/755,436, filed 26 Feb. 2018, which is a national phase application ofand claims the benefit of International Application PCT/IB2016/055274,filed on 2 Sep. 2016, which is based on and claims the benefit of IndianProvisional Application Nos. 4640/CHE/2015, filed on 2 Sep. 2015,entitled “An improved process for preparation of ivacaftor”,5222/CHE/2015, filed on 30 Sep. 2015, entitled “A process forpreparation of ivacaftor”, and 5696/CHE/2015 filed on 23 Oct. 2015,entitled “A process for preparation of ivacaftor”, the content of eachof which are incorporated by reference herein.

FIELD OF THE INVENTION

The present invention generally relates to processes for the preparationof ivacaftor or a pharmaceutically acceptable salt thereof using novelintermediates.

BACKGROUND OF THE INVENTION

The drug compound having the adopted name Ivacaftor, has a chemical nameN-(2,4-di-tert-butyl-5-hydroxyphenyl)-1,4-dihydro-4-oxoquinoline-3-carboxamide,and is represented by following Formula I:

Ivacaftor was approved by FDA and marketed by Vertex pharma for thetreatment of cystic fibrosis under the brand name KALYDECO® in the formof 150 mg oral tablets and in combination with lumacaftor under thebrand name ORKAMBI® in the form of 200 mg/125 mg tablets(Lumacaftor/Ivacaftor) for the treatment of cystic fibrosis.

U.S. Pat. No. 7,495,103 (“the '103 patent”) discloses modulators ofATP-binding cassette transporters such as ivacaftor. The '103 patentfurther discloses a process for the preparation of modulators ofATP-binding cassette transporters such as quinoline compounds; however,ivacaftor process was not specifically disclosed. The '103 patentprocess includes condensation of 4-oxo-1,4-dihydro-3-quinolinecarboxylic acid with aniline in presence of a coupling reagent such as1-[bis(dimethylamino) methylene]-1H-1,2,3-triazolo[4,5-b ]pyridinium3-oxid hexafluorophosphate (HATU), N,N-diisopropylethylamine (DIEA) indimethylformamide and then purifying the obtained compound by HPLC. Theprocess disclosed in the '103 patent is schematically represented asfollows:

U.S. Pat. No. 8,410,274 (“the '274 patent”) specifically discloses aprocess for preparation of ivacaftor, which involves condensation of4-oxo-1,4-dihydro-3-quinoline carboxylic acid with5-amino-2,4-di-(tert-butyl)phenol in presence of a coupling reagent suchas HBTU, triethylamine and dimethyl formamide to obtain ivacaftor. Theprocess disclosed in the '274 patent is schematically represented asfollows:

U.S. Pat. No. 8,476,442 (“the '442 patent”) discloses a process forpreparation of ivacaftor, which involves the coupling of4-oxo-1,4-dihydro-3-quinoline carboxylic acid with hydroxyl protectedamine intermediate in the presence of a coupling reagent such as propanephosphonic anhydride (T₃P®) and pyridine followed by deprotection ofhydroxyl protection group to obtain ivacaftor. The process disclosed inthe '442 patent is schematically represented as follows:

China Patent publication No. 103044263 (“the '263 publication”)discloses a process for the preparation of ivacaftor, which involves thecoupling of 4-oxo-1,4-dihydro-3-quinoline carboxylic acid chloride withhydroxyl protected amine intermediate in the presence of triethylaminein methylene chloride followed by deprotection of the hydroxylprotection group to obtain ivacaftor. The process disclosed in the '263publication is schematically represented as follows:

China Patent publication No. 103787968 (“the '968 publication”)discloses a process for the preparation of ivacaftor, which involves thecoupling of 4-oxo-1,4-dihydro-3-quinoline carboxylic acid ethyl esterwith hydroxyl protected amine intermediate in the presence of ethanolfollowed by deprotection of hydroxyl protection group to obtainivacaftor. The process disclosed in the '968 publication isschematically represented as follows:

PCT Publication No. WO2014/118805 (“the '805 publication”) discloses aprocess for the preparation of ivacaftor, which involves reaction ofmalonate intermediate with 5-amino-2,4-di-(tert-butyl)phenol to obtainester intermediate and finally cyclized to obtain ivacaftor. The processdisclosed in the '805 publication is schematically represented asfollows:

PCT Publication No. WO2014/125506 (“the '506 publication”) discloses aprocess for the preparation of ivacaftor, which involves condensation of1-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxylic acid with5-amino-2,4-di-(tert-butyl)phenol in the presence of an amide couplingreagent such as HATU in dimethylformamide and followed by deprotectionto obtain ivacaftor. The process disclosed in the '506 publication isschematically represented as follows:

PCT Publication No. WO2014/135096 (“the '096 publication”) discloses aprocess for the preparation of ivacaftor by following methods:

PCT Publication No. WO2015/128882 (“the '882 publication”) discloses aprocess for the preparation of ivacaftor, which involves condensation of4-oxo-1,4-dihydro-3-quinoline carboxylic acid with5-amino-2,4-di-(tert-butyl)phenol in presence of a coupling reagent suchas EDC HCl and HOBt, triethylamine and dimethyl formamide to obtainivacaftor. The process disclosed in the '882 patent is schematicallyrepresented as follows:

CN Publication No. CN105130891A (“the '891 publication”) discloses aprocess for the preparation of ivacaftor. The process disclosed in the'891 publication is schematically represented as follows:

The reported literatures for the preparation of ivacaftor have certaindrawbacks, which include use of coupling agents in the amide formationreaction. The use of coupling agents in such a reaction creates unwantedby-products as well as unreacted coupling agents as contaminants,thereby extensive purifications are required in order to eliminate suchcompounds from the pure product.

There is a need in the art to develop an improved process for thepreparation of ivacaftor, which is readily amenable to large scaleproduction. The present inventors focused improved processes for thepreparation of ivacaftor with greater yield and higher purity, whichprocess avoids the expensive coupling agents.

SUMMARY OF THE INVENTION

In accordance with one embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof:

comprising:

-   -   a) reacting a compound of Formula III with a compound of Formula        IV or a salt thereof to obtain a compound of Formula V, and

-   -   b) optionally deprotecting the compound of Formula V to obtain        ivacaftor of Formula I; wherein ‘R’ represents hydrogen or a        suitable cleavable group, and ‘X’ represents a suitable leaving        group.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof, comprising:

-   -   a) reacting a compound of Formula III with a compound of Formula        IV or a salt thereof to obtain a compound of Formula V, wherein        ‘R’ represents hydrogen or a suitable cleavable group, ‘X’        represents chloro, bromo or iodo; and    -   b) optionally deprotecting the compound of Formula V to obtain        ivacaftor of Formula I.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof,

comprising:

-   -   a) reacting a compound of Formula II with a source of suitable        leaving group to obtain a compound of Formula III,

-   -   b) reacting the compound of Formula III with a compound of        Formula IV or a salt thereof to obtain a compound of Formula V,        and

-   -   c) optionally deprotecting the compound of Formula V to obtain        ivacaftor of Formula I; wherein ‘R’ represents hydrogen or a        suitable cleavable group, and ‘X’ represents a suitable leaving        group.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof:

comprising:

-   -   a1) reacting a compound of Formula VI with dimethyl        formamide-dimethyl amine complex to obtain a compound of Formula        VII,

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group;

-   -   b1) reacting the compound of Formula VII with a source of        ammonia to obtain a compound of Formula VIII, and

-   -   c1) cyclizing the compound of Formula VIII to obtain Ivacaftor,        when R₁ is hydrogen, or to obtain a compound of Formula IX, when        R₁ is a protecting group and then deprotecting the Formula IX to        obtain ivacaftor.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof:

comprising:

-   -   a2) reacting a compound of Formula VIb with dimethyl        formamide-dimethyl amine complex to obtain a compound of Formula        VIIb,

-   -   b2) reducing the compound of Formula VIIb in presence of a        suitable reducing agent to obtain a compound of Formula X, and

-   -   c2) converting the compound of Formula X in to ivacaftor.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof;

comprising:

-   -   a3) reacting a compound of Formula XI with a compound of Formula        IVa or a salt thereof to obtain a compound of Formula VI, and

-   -   b3) converting the compound of Formula VI in to ivacaftor;        wherein when ‘X’ is halo, then ‘R1’ is either hydrogen or a        suitable protecting group; and when ‘X’ is nitro, then ‘R₁’ is        hydrogen.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof; comprising:

-   -   a4) reacting the compound of Formula XII with a compound of        Formula IVa or a salt thereof to obtain a compound of Formula        VI, and

-   -   b4) converting the compound of Formula VI in to ivacaftor;        wherein when ‘X’ is halo, then ‘R₁’ is either hydrogen or a        suitable protecting group; when ‘X’ is nitro, then ‘R₁’ is        hydrogen; and wherein “Z” represents C₁-C₅ alkoxy or halogen.

In accordance with another embodiment, the present invention provides acompound of Formula VI or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula VIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula VIa or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIp′ or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIb or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VII or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula VIIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula VIIa or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIIp′ or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIIb or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIII or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula VIIIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula Villa or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula VIIIp′ or a pharmaceutically acceptable saltthereof.

In accordance with another embodiment, the present invention provides acompound of Formula Xp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In accordance with another embodiment, the present invention provides acompound of Formula X or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula Xp′ or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof,

comprising:

-   -   a5) reacting a compound of Formula VI with (C₁₋₅        alkyl)₃-orthoformate to obtain a compound of Formula XIII.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group and wherein ‘R₂’ represents C₁₋₅ alkyl;

-   -   b5) reacting the compound of Formula XIII with a source of        ammonia to obtain a compound of Formula VIII, and

-   -   c5) cyclizing the compound of Formula VIII to obtain ivacaftor,        when R₁ is hydrogen, or to obtain a compound of Formula IX, when        R₁ is a protecting group and deprotecting the Formula IX to        obtain Ivacaftor.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof, comprising:

-   -   a6) reacting a compound of Formula VIb with (C₁₋₅        alkyl)₃-orthoformate to obtain a compound of Formula XIV,        wherein ‘R₂’ represents C₁₋₅ alkyl,

-   -   b6) reducing the compound of Formula XIV in presence of a        suitable reducing agent to obtain a compound of Formula XV, and

-   -   c6) cyclizing the compound of Formula XV in to ivacaftor.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof;

comprising:

-   -   a7) reacting a compound of Formula XVI with a compound of        Formula IVa or a salt thereof to obtain a compound of Formula        XVII,

-   -   b7) reacting the compound of Formula XVII with a compound of        Formula XVIII to obtain a compound of Formula XIII, and

-   -   c7) converting the compound of Formula XIII in to ivacaftor;        wherein ‘X’ represents halo or nitro; ‘R₁’ represents either        hydrogen or a suitable protecting group; ‘R₂’ represents C₁₋₅        alkyl; L and L′ represents a suitable leaving group.

In accordance with another embodiment, the present invention provides acompound of Formula XIII or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents Halo, —NO₂ or —NH₂, ‘R₁’ represents eitherhydrogen or a suitable protecting group; and ‘R₂’ represents C₁₋₅ alkyl;provided that wherein when “X” is —NO₂ or —NH₂ then ‘R₁’ is hydrogen.

In accordance with another embodiment, the present invention provides acompound of Formula XIIIa or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula XIIIb or a pharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula XIIIc, wherein ‘R₂’ represents C₁₋₅ alkyl, or apharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides acompound of Formula XV, wherein ‘R₂’ represents C₁₋₅ alkyl, or apharmaceutically acceptable salt thereof.

In accordance with another embodiment, the present invention provides apharmaceutical composition comprising ivacaftor or a pharmaceuticallyacceptable salt thereof prepared by the processes of the presentinvention and at least one pharmaceutically acceptable excipient.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process for the preparation ofivacaftor or a pharmaceutically acceptable salt thereof using novelintermediates.

In accordance with one embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof:

comprising:

-   -   a) reacting a compound of Formula III with a compound of Formula        IV or a salt thereof to obtain a compound of Formula V, and

-   -   b) optionally deprotecting the compound of Formula V to obtain        ivacaftor of Formula I;

wherein ‘R’ represents hydrogen or a suitable cleavable group and ‘X’represents a suitable leaving group.

In accordance with another embodiment, the present invention provides aprocess for the preparation of ivacaftor of Formula I or apharmaceutically acceptable salt thereof,

comprising:

-   -   a) reacting a compound of Formula II with a source of suitable        leaving group to obtain a compound of Formula III,

-   -   b) reacting the compound of Formula III with a compound of        Formula IV or a salt thereof to obtain a compound of Formula V,        and

-   -   c) optionally deprotecting the compound of Formula V to obtain        ivacaftor of Formula I;

wherein ‘R’ represents hydrogen or a suitable cleavable group and ‘X’represents a suitable leaving group.

Unless otherwise specified, the term “suitable cleavable group” usedherein the specification includes but is not limited to carbamates suchas tertiary butyloxy carbonyl (Boc), carboxy benzoyl (Cbz),fluorenylmethyloxycarbonyl (Fmoc), allyloxycarbonyl (alloc), methyl andethyl carbamates; cyclic imide derivatives such as phthalimide; amidessuch as formyl; acetyl, pivaloyl, trityl; substituted or unsubstitutedaryls such as benzyl, benzoyl, p-nitrobenzoyl (PNB), p-phenyl benzyl(PPB), 4-methoxy benzyl, 4-trifluoromethyl benzyl, 4-chloro benzyl; andtrialkyl silyl groups such as trimethylsilyl (TMS),tert-butyldiphenylsilyl (TBDPS), tert-butyldimethylsilyl (TBS/TBDMS),triisopropylsilyl (TIPS) and the like.

Unless otherwise specified, the term “suitable leaving group” usedherein the specification includes but is not limited to chloro, bromo,iodo and the like; mesyl, tosyl, triflate, nosyl and the like.

Unless otherwise specified, the term “source of suitable leaving group”used herein the specification includes but is not limited to thionylchloride, thionyl bromide, phosphorous oxy chloride, phosphorouspentachloride, phosphorous tribromide, oxalyl chloride, phosphorustriiodide and the like; halides of mesyl, tosyl, nosyl such as chloro,bromo, iodo and the like; triflic acid.

Compound of Formula II and compound of Formula IV or a salt thereof areknown in the art and can be prepared by any method known in the art, forexample compound of Formula II may be prepared by using the processdisclosed in WO2014/125506, and compound of Formula IV or a salt thereofmay be prepared by using the process disclosed in applicant's PCTapplication No. 2016/075703.

The step a) of the aforementioned process involves reaction of compoundof Formula II; wherein ‘R’ represents hydrogen or a suitable cleavablegroup, with a source of suitable leaving group, may be carried out in asuitable solvent and in presence of a suitable base to obtain a compoundof Formula III; wherein ‘X’ represents a suitable leaving group asmentioned above; preferably chloro or bromo; more preferably chloro.

In a preferred embodiment, the compound of Formula II is used as bothprotected or unprotected groups at nitrogen and in case of formula IIhas protecting group at nitrogen atom an optional step of deprotectionstep is necessary to obtain ivacaftor of Formula I. The suitablecleavable group used herein preferably benzyl group.

The suitable solvent for the reaction of compound of Formula II; wherein‘R’ defined as above with a source of suitable leaving group, includesbut is not limited to ethers, halogenated solvents, aromatichydrocarbons, amides, sulfoxides, nitriles and mixtures thereof.Preferably ethers include, but are not limited to tetrahydrofuran,2-methyl tetrahydrofuran, dimethyl ether, diisopropyl ether, methyltertiary butyl ether, 1,4-dioxane and the like; halogenated solventsinclude, but are not limited to methylene chloride, ethylene chloride,chloroform and the like; aromatic hydrocarbons include, but are notlimited to toluene, xylene and the like; amides include, but are notlimited to dimethyl formamide, dimethyl acetamide, N-methylpyrrolidinone and the like; sulfoxides include, but are not limited todimethylsulfoxide, sulfolane and the like; nitriles include, but are notlimited to acetonitrile, propionitrile and like and mixtures thereof;preferably methylene chloride, tetrahydrofuran or dimethyl formamide.

Exemplary bases used herein for the reaction of compound of Formula II;wherein ‘R’ defined as above with a source of suitable leaving group,includes but are not limited to sodium hydroxide, potassium hydroxide,sodium methoxide, sodium ethoxide, sodium-tert-butoxide,potassium-tert-butoxide, sodium carbonate, potassium carbonate, cesiumcarbonate, sodium bicarbonate, potassium bicarbonate, triethylamine,isopropyl ethylamine, diisopropyl amine, diisopropyl ethylamine,N-methyl morpholine, piperidine, pyridine and the like and mixturesthereof; preferably triethylamine, sodium hydroxide or diisopropylethylamine.

The reaction of compound of Formula II; wherein ‘R’ defined as abovewith a source of suitable leaving group is carried out at a temperatureof about 0° C. to reflux temperature; preferably at 35° C. to about 40°C.

The step b) of the aforementioned process involves reaction of thecompound of Formula III; wherein ‘R’ and ‘X’ are defined as above, witha compound of Formula IV or a salt thereof, may be carried out in asuitable solvent and in presence of a suitable base to obtain a compoundof Formula V; wherein ‘R’ defined as above.

The suitable solvent for the reaction of compound of Formula III;wherein ‘R’ and ‘X’ are defined as above, with a compound of Formula IVor a salt thereof may be carried out in a suitable solvent. The suitablesolvent includes but is not limited to ethers, halogenated solvents,aromatic hydrocarbons, amides, sulfoxides, nitriles and mixturesthereof. Preferably ethers include, but are not limited totetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl ether, diisopropylether, methyl tertiary butyl ether, 1,4-dioxane and the like;halogenated solvents include, but are not limited to methylene chloride,ethylene chloride, chloroform and the like; aromatic hydrocarbonsinclude, but are not limited to toluene, xylene and the like; amidesinclude, but are not limited to dimethylformamide, dimethyl acetamide,N-methyl pyrrolidinone and the like; sulfoxides include, but are notlimited to dimethylsulfoxide, sulfolane and the like; nitriles include,but are not limited to acetonitrile, propionitrile and like and mixturethereof; preferably methylene chloride, tetrahydrofuran ordimethylformamide.

Exemplary bases used herein for the reaction of compound of Formula III;wherein ‘R’ and ‘X’ are defined as above, with a compound of Formula IVor a salt thereof, includes but are not limited to sodium hydroxide,potassium hydroxide, sodium methoxide, sodium ethoxide,sodium-tert-butoxide, potassium-tert-butoxide, sodium carbonate,potassium carbonate, cesium carbonate, sodium bicarbonate, potassiumbicarbonate, triethylamine, isopropylethylamine, diisopropyl amine,diisopropyl ethylamine, N-methyl morpholine, piperidine, pyridine andthe like and mixture thereof; preferably triethylamine, diisopropylethylamine or potassium hydroxide.

The reaction of compound of Formula III; wherein ‘R’ and ‘X’ are definedas above, with a compound of Formula IV or a salt thereof is carried outat a temperature of about 0° C. to reflux temperature; preferably at 25°C. to about 40° C.

The step c) of the aforementioned process involves optional step ofdeprotection of the compound of Formula V; when R is a protecting groupwhich is mentioned as above to obtain ivacaftor of Formula I or apharmaceutically acceptable salt thereof. The deprotection is carriedout in presence of a suitable deprotecting agent and a suitable solvent.

The suitable deprotecting agent used herein for the deprotection of thecompound of Formula V; wherein ‘R’ defined as above includes but is notlimited to palladium on carbon, palladium hydroxide, raney nickel,platinum oxide, cericammoniumnitrate (CAN) in presence of hydrogensource such as ammonium formate or hydrogen gas,2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetrabutylammonium fluoride,borantribromide, aluminium chloride, acid source such as HCl, HBr,acetic acid, trifluoroacetic acid and the like.

The suitable solvent for deprotection of the compound of Formula V;wherein ‘R’ defined as above includes but is not limited to alcohols,ketones, nitriles, ethers, amides and mixtures thereof. The alcoholsinclude, but are not limited to methanol, ethanol, isopropanol and thelike; ketones include, but are not limited to acetone, methyl isobutylketone, methyl ethyl ketone and the like; nitriles include, but are notlimited to acetonitrile, propionitrile and the like; ethers include, butare not limited to tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylether, diisopropyl ether, methyl tertiary butyl ether, 1,4-dioxane andthe like; amides include, but are not limited to dimethyl formamide,dimethyl acetamide, N-methyl pyrrolidinone and the like and mixturethereof; preferably dimethyl formamide.

The deprotection reaction may be carried out at a temperature of about0° C. to reflux temperature; preferably at 60° C. to about 90° C.

In another embodiment, the present invention provides a process for thepreparation of ivacaftor of Formula I or a pharmaceutically acceptablesalt thereof:

comprising:

-   -   a1) reacting a compound of Formula VI with dimethyl        formamide-dimethyl amine complex to obtain a compound of Formula        VII,

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group;

-   -   b1) reacting the compound of Formula VII with a source of        ammonia to obtain a compound of Formula VIII, and

-   -   c1) cyclizing the compound of Formula VIII to obtain ivacaftor,        when R₁ is hydrogen, or to obtain a compound of Formula IX, when        R₁ is a protecting group and deprotecting the Formula IX to        obtain ivacaftor.

In another embodiment, the starting compound of Formula VI can beprepared according to process described in one or more below mentionedembodiments.

The step a1) of the aforementioned process involves reaction of compoundof Formula VI, obtained by the processes described as above withdimethyl formamide-dimethyl amine complex in a suitable organic solvent;wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In a preferred embodiment the exemplary compound of Formula VII can berepresented as follows:

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In a further preferred embodiment the exemplary compound of Formula VIIcan be represented as follows:

The suitable organic solvent used herein for reaction of compound ofFormula VI with dimethyl formamide-dimethyl amine complex includes butis not limited to nitriles, ethers, aromatic hydrocarbons and mixturesthereof. The nitriles include, but are not limited to acetonitrile,propionitrile and the like; ethers include, but are not limited totetrahydrofuran, dimethyl ether, methyl tertiary butyl ether,dimethoxyethane and the like; aromatic hydrocarbons include, but are notlimited to toluene, xylene and the like and mixtures thereof; preferablytoluene.

The reaction of compound of Formula VI with dimethyl formamide-dimethylamine complex advantageously carried out at a temperature of about roomtemperature to reflux temperature; preferably 50° C. to about 75° C.

The step b1) of the aforementioned process involves reaction of thecompound of Formula VII with a source of ammonia to obtain a compound ofFormula VIII, wherein ‘X’ and ‘R₁’ are defined as above.

In a preferred embodiment the exemplary compound of Formula VIII can berepresented as follows:

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In a further preferred embodiment the exemplary compound of Formula VIIIcan be represented as follows:

Exemplary sources of ammonia used herein for the reaction of compound ofFormula VII includes but is not limited to ammonia gas, ammoniumhydroxide, ammonium acetate, ammonium formate and the like; preferablyammonium hydroxide.

The reaction of the compound of Formula VII with a source of ammonia maybe carried out in a suitable solvent. The suitable solvent includes butis not limited to alcohols, amides, aromatic hydrocarbons, water andmixtures thereof. The alcohols include, but are not limited to methanol,ethanol, isopropanol and the like; amides include, but are not limitedto dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidinone andthe like; aromatic hydrocarbons include, but are not limited to toluene,xylene and the like; water and mixtures thereof; preferably ethanol.

The reaction of the compound of Formula VII with a source of ammoniaadvantageously carried out at a temperature of about room temperature toreflux temperature; preferably at 20° C. to about 40° C.

The step c1) of the aforementioned process involves cyclization of thecompound of Formula VIII to obtain ivacaftor, when R₁ is hydrogen, or toobtain a compound of Formula IX, when R₁ is a protecting group anddeprotecting the Formula IX to obtain ivacaftor.

The cyclization of compound of Formula VIII is carried out in presenceof a suitable base to obtain a compound of Formula IX. The suitable baseincludes but is not limited to inorganic bases such as sodium hydroxide,potassium hydroxide, sodium methoxide, sodium ethoxide, sodiumtert-butoxide, potassium tert-butoxide, sodium carbonate, potassiumcarbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate,organic bases such as triethylamine, isopropylethylamine,diisopropylamine, diisopropylethylamine, N-methylmorpholine, piperidine,pyridine and the like and mixtures thereof; preferably potassiumhydroxide.

The cyclization of compound of Formula VIII is carried out in a suitablesolvent. The suitable solvent includes but is not limited to ethers,alcohols, aromatic hydrocarbons, amides, sulfoxides, nitriles andmixtures thereof. Preferably ethers include, but are not limited totetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl ether, methyltertiary butyl ether and the like; alcohols include, but are not limitedto methanol, ethanol, isopropanol and the like; aromatic hydrocarbonsinclude, but are not limited to toluene, xylene and the like; amidesinclude, but are not limited to dimethylformamide, dimethyl acetamide,N-methyl pyrrolidinone and the like; sulfoxides include, but are notlimited to dimethylsulfoxide, sulfolane and the like; nitriles include,but are not limited to acetonitrile, propionitrile and like and mixturesthereof; preferably dimethylformamide.

The deprotection of the compound of Formula IX is carried out inpresence of a suitable deprotecting agent and a suitable solvent.

The suitable deprotecting agent used herein for the deprotection of thecompound of Formula IX; wherein ‘R₁’ defined as above includes but isnot limited to acid deprotecting agent such as hydrochloric acid,hydrobromic acid, trifluoro acetic acid and the like and mixturethereof; base deprotecting agent such as potassium carbonate, sodiumhydroxide, sodium ethoxide and the like and mixture thereof; preferablypotassium carbonate.

The suitable solvent for deprotection of the compound of Formula IX;wherein ‘R₁’ defined as above includes but is not limited to alcohols,ketones, ethers, amides, sulfoxides and mixtures thereof. The alcoholsinclude, but are not limited to methanol, ethanol, isopropanol and thelike; ketones include, but are not limited to acetone, methyl isobutylketone, methyl ethyl ketone and the like; ethers include, but are notlimited to tetrahydrofuran, 2-methyl tetrahydrofuran, methyl tertiarybutyl ether and the like; amides include, but are not limited todimethyl formamide, dimethyl acetamide, N-methyl pyrrolidinone and thelike; sulfoxides include, but are not limited to dimethylsulfoxide,sulfolane and the like and mixture thereof; preferably dimethylformamide.

The deprotection reaction may be carried out at a temperature of about0° C. to reflux temperature; preferably at 90° C. to about 110° C.

In another embodiment, the present invention provides a process for thepreparation of compound of Formula VI, comprising: reacting a compoundof Formula XI with a compound of Formula IVa or a salt thereof to obtaina compound of Formula VI;

wherein when ‘X’ is halo, then ‘R₁’ is either hydrogen or a suitableprotecting group; and when ‘X’ is nitro, then ‘R₁’ is hydrogen.

Unless otherwise specified the term suitable hydroxy protecting groupused herein are selected from methoxycarbonyl, methoxymethyl (MOM),benzyloxymethyl (BOM), tetrahydropyranyl (THP), benzyl (Bn), benzoyl(Bz), p-methoxybenzyl (PMB), p-nitrobenzyl, o-nitrobenzyl,p-nitrobenzoyl (PNB), trimethylsilyl (TMS) and the like.

Unless otherwise specified the term ‘C₁-C₅ alkoxy’ represents methoxy,ethoxy, isopropoxy, butyloxy and pentyloxy.

Unless otherwise specified the term ‘halo’ represents fluoro, chloro,bromo or iodo.

The aforementioned process involves reaction of compound of Formula XIwith a compound of Formula IVa or a salt thereof in presence of asuitable base and in a suitable solvent to obtain a compound of FormulaVI; wherein when ‘X’ is halo, then ‘R₁’ is either hydrogen or a suitableprotecting group; and when ‘X’ is nitro, then ‘R₁’ is hydrogen.

In a preferred embodiment the exemplary compound of Formula XI, FormulaIVa and Formula VI can be represented as follows:

The compound of Formula XIa and compound of Formula IVa or a saltthereof known in the art and can be prepared by any method known in theart, for example compound of Formula XI may be prepared by the processdisclosed in Archiv der Pharmazie, 2013, vol 346, 7, page 521-533 or bythe process described in below examples; and compound of Formula IVa ora salt can be prepared by using the process disclosed in applicant's PCTapplication No. 2016/075703.

Exemplary bases used herein for the reaction of a compound of FormulaXIa or Formula XIb with a compound of Formula IV or a salt thereof,includes but are not limited to inorganic bases such as sodiumhydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide,sodium tert-butoxide, potassium tert-butoxide, sodium carbonate,potassium carbonate, cesium carbonate, sodium bicarbonate, potassiumbicarbonate, organic bases such as triethylamine, isopropylethylamine,diisopropylamine, diisopropylethylamine, N-methylmorpholine, piperidine,pyridine and the like and mixtures thereof; preferablydiisopropylethylamine.

The suitable solvent for the reaction of a compound of Formula XIa orFormula XIb with a compound of Formula IV or a salt thereof, include butis not limited to amides, halogenated hydrocarbons, aromatichydrocarbons and mixtures thereof. The amides include, but are notlimited to dimethyl formamide, dimethyl acetamide, N-methylpyrrolidinone and the like; halogenated hydrocarbons include, but arenot limited to methylene chloride, ethylene chloride and the like;aromatic hydrocarbons include, but are not limited to toluene, xyleneand the like and mixtures thereof; preferably toluene.

The reaction of Formula XIa or Formula XIb with a compound of Formula IVor a salt is advantageously carried out at a temperature of about roomtemperature to reflux temperature; preferably at 90° C. to about 110° C.

The resultant compound of Formula VI (preferably Formula VIa, FormulaVIp′ or Formula VIb) can be isolated by conventional methods; forexample concentration of the reaction mass under reduced pressure toobtain solid compound as crude, which can be optionally separated byadding suitable hydrocarbon solvent such as hexane, heptane, cyclohexaneand the like; preferably heptane and then filtering the product.

In another embodiment, the present invention provides a process for thepreparation of compound of Formula VI, comprising: reacting the compoundof Formula XII with a compound of Formula IVa or a salt thereof toobtain a compound of Formula VI,

wherein when ‘X’ is halo, then ‘R₁’ is either hydrogen or a suitableprotecting group; when ‘X’ is nitro, then ‘R₁’ is hydrogen; and wherein“Z” represents C₁-C₅ alkoxy or halogen.

The aforementioned process involves reaction of compound of Formula XIIwith a compound of Formula IVa or a salt thereof in presence of asuitable base and in a suitable solvent to obtain a compound of FormulaVI.

In a preferred embodiment the exemplary compound of Formula XII, FormulaIVa and Formula VI can be represented as follows:

The compound of Formula XII is known in the art and can be prepared byany method known in the art, for example may be prepared by the processdisclosed in Journal of Heterocyclic Chemistry, 2011, vol 48, 3, page620-625, Bioorganic and Medicinal Chemistry, 2013, vol 21, 11, page2843-2855 or by the process described in below examples.

The base and solvent used herein for reaction of compound of FormulaXIIa or Formula XIIb with a compound of Formula IV or a salt thereof issame as used for the reaction of compound of Formula XIa or Formula XIbwith a compound of Formula IV or a salt thereof as mentioned above.

The reaction of Formula XIIa or Formula XIIb with a compound of FormulaIV or a salt is advantageously carried out at a temperature of aboutroom temperature to reflux temperature; preferably at 90° C. to about110° C.

The resultant compound of Formula VI (preferably Formula VIa, FormulaVIp′ or Formula VIb) can be isolated by conventional methods; forexample concentration of the reaction mass under reduced pressure toobtain solid compound as crude, which can be optionally separated byadding suitable hydrocarbon solvent such as hexane, heptane, cyclohexaneand the like; preferably heptane and then filtering the product.

The compound of Formula VI, preferably a compound of Formula VIa,Formula VIp′ or Formula VIb obtained by the processes described just asabove can be used as intermediate in the preparation of ivacaftor of theinvention.

In another embodiment, the present invention provides a process for thepreparation of ivacaftor of Formula I or a pharmaceutically acceptablesalt thereof: comprising:

-   -   a2) reacting a compound of Formula VIb with dimethyl        formamide-dimethyl amine complex to obtain a compound of Formula        VIIb,

-   -   b2) reducing the compound of Formula VIIb in presence of a        suitable reducing agent to obtain a compound of Formula X, and

-   -   c2) converting the compound of Formula X in to ivacaftor.

The compound of Formula VIb may be prepared by the processes describedas above of the present invention.

The step a2) of the aforementioned process involves reaction of compoundof Formula VIb with dimethyl formamide-dimethyl amine complex to obtaina compound of Formula VIIb is same as the process described for thepreparation of compound of Formula VIIa.

The step b2) of the aforementioned process involves reduction of thecompound of Formula VIIb in presence of a suitable reducing agent toobtain a compound of Formula X.

The suitable reducing agent used herein is selected from the groupconsisting of Fe/ammonium chloride, Fe/ammonium formate, Fe/HCl,hydrogen gas, palladium on carbon, raney nickel, platinum oxide, sodiumhydrosulfite, zinc and the like; preferably Fe/ammonium chloride.

The reduction of the compound of Formula VIIb is carried out in asuitable solvent. The suitable solvent includes but is not limited toethers, alcohols, amides, sulfoxides, water and mixtures thereof.Preferably ethers include, but are not limited to tetrahydrofuran,2-methyltetrahydrofuran, dimethyl ether, methyl tertiary butyl ether andthe like; alcohols include, but are not limited to methanol, ethanol,isopropanol and the like; amides include, but are not limited todimethylformamide, dimethyl acetamide, N-methyl pyrrolidinone and thelike; sulfoxides include, but are not limited to dimethylsulfoxide,sulfolane and the like; water and mixtures thereof; preferably ethanol.

The reduction of the compound of Formula VIIb advantageously carried outat a temperature of about room temperature to reflux temperature;preferably at 55° C. to about 80° C.

The step c2) of the aforementioned process involves convertion of thecompound of Formula X in to ivacaftor.

In an embodiment, the process of step c2) of conversion of the compoundof Formula X in to ivacaftor is carried out incisively without isolatingthe compound of Formula X.

In another embodiment, the present invention provides a compound ofFormula VI or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIa a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIp′ or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIb or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VII or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIIa or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIIp′ or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIIb or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIII or a pharmaceutically acceptable salt thereof.

wherein ‘X’ represents halo and ‘R₁’ represents either hydrogen or asuitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIIIp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In another embodiment, the present invention provides a compound ofFormula VIIIa or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula VIIIp′ or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula Xp or a pharmaceutically acceptable salt thereof.

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In another embodiment, the present invention provides a compound ofFormula X or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula Xp′ or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a process for thepreparation of ivacaftor of Formula I or a pharmaceutically acceptablesalt thereof:

comprising:

-   -   a5) reacting a compound of Formula VI with (C₁₋₅        alkyl)₃-orthoformate to obtain a compound of Formula XIII,

wherein ‘X’ represents halo; ‘R₁’ represents either hydrogen or asuitable protecting group;

and ‘R₂’ represents C₁₋₅ alkyl;

-   -   b5) reacting the compound of Formula XIII with a source of        ammonia to obtain a compound of Formula VIII, and

-   -   c5) cyclizing the compound of Formula VIII to obtain ivacaftor,        when R₁ is hydrogen, or to obtain a compound of Formula IX, when        R₁ is a protecting group and deprotecting the Formula IX to        obtain ivacaftor.

Unless otherwise specified the term suitable hydroxy protecting groupused herein are selected from methoxycarbonyl, methoxymethyl (MOM),benzyloxymethyl (BOM), tetrahydropyranyl (THP), benzyl (Bn), benzoyl(Bz), p-methoxybenzyl (PMB), p-nitrobenzyl, o-nitrobenzyl,p-nitrobenzoyl (PNB), trimethylsilyl (TMS) and the like.

Unless otherwise specified the term ‘halo’ represents fluoro, chloro,bromo or iodo.

Unless otherwise specified the term ‘suitable leaving group’ representshalogen such as fluoro, chloro, bromo, iodo or mesyl, tosyl and thelike.

Unless otherwise specified the term ‘C₁₋₅ alkyl’ represents methyl,ethyl, propyl, butyl and pentyl.

The compound of Formula VI (preferably Formula VIa or Formula VIb) canbe prepared by using the process disclosed in applicant's PCTapplication No. 2016/075730.

In a preferred embodiment the exemplary compound of Formula VI can berepresented as follows:

The step a5) of the aforementioned process involves reaction of compoundof Formula VI with (C₁₋₅ alkyl)₃-orthoformate in presence of a suitableLewis acid; wherein ‘X’ represents halo and ‘R₁’ represents eitherhydrogen or a suitable protecting group to obtain a compound of FormulaXIII.

In a further preferred embodiment the exemplary compound of Formula XIIIcan be represented as follows:

The suitable (C₁₋₅ alkyl)₃-orthoformate used herein for step a5)includes but is not limited to trimethyl orthoformate, triethylorthoformate, tripropyl orthoformate, tributyl orthoformate, tripentylorthoformate and the like; preferably triethyl orthoformate.

The suitable Lewis acid used herein for step a5) includes but is notlimited to zinc chloride, tin(IV) chloride, tin(II) chloride, aluminiumchloride, boron trifluoride and the like; preferably zinc chloride.

The reaction of compound of Formula VI with (C₁₋₅ alkyl)₃-orthoformatemay be optionally carried out in a suitable solvent, which includes butis not limited to acid anhydride, nitriles, ethers, aromatichydrocarbons and mixtures thereof. The acid anhydride include, but arenot limited to acetic anhydride, propionic anhydride and the like;nitriles include, but are not limited to acetonitrile, propionitrile andthe like; ethers include, but are not limited to tetrahydrofuran,dimethyl ether, methyl tertiary butyl ether, dimethoxyethane and thelike; aromatic hydrocarbons include, but are not limited to toluene,xylene and the like and mixtures thereof; preferably acetic anhydride.

The reaction of compound of Formula VI with (C₁₋₅ alkyl)₃-orthoformateadvantageously carried out at a temperature of about room temperature toreflux temperature; preferably at 20° C. to about 40° C.

After completion of the reaction, the resultant compound of Formula XIIImay be isolated by known techniques, for example the reaction masscontaining compound of Formula XIII may be quenched with water followedby extracting the product with a suitable water immiscible solvent suchas ethyl acetate, methylene chloride or toluene; preferably ethylacetate and then evaporating the solvent completely under normal orreduced pressure to obtain a compound of Formula XIII.

The step b5) of the aforementioned process involves reaction of thecompound of Formula XIII with a source of ammonia to obtain a compoundof Formula VIII, wherein ‘X’ and ‘R₁’ are defined as above.

In a preferred embodiment the exemplary compound of Formula VIII can berepresented as follows:

wherein ‘R₁’ represents either hydrogen or a suitable protecting group.

In a further preferred embodiment the exemplary compound of Formula VIIIcan be represented as follows:

Exemplary sources of ammonia used herein for the reaction of compound ofFormula XIII includes but is not limited to ammonia gas, ammoniumhydroxide, ammonium acetate, ammonium formate and the like; preferablyammonium hydroxide.

The reaction of the compound of Formula XIII with a source of ammoniamay be carried out in a suitable solvent. The suitable solvent includesbut is not limited to alcohols, amides, aromatic hydrocarbons, water andmixtures thereof. The alcohols include, but are not limited to methanol,ethanol, isopropanol and the like; amides include, but are not limitedto dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidinone andthe like; aromatic hydrocarbons include, but are not limited to toluene,xylene and the like; water and mixtures thereof; preferably ethanol.

The reaction of the compound of Formula XIII with a source of ammoniaadvantageously carried out at a temperature of about room temperature toreflux temperature; preferably at 70° C. to about 80° C.

The resultant compound of Formula VIII obtained after step b5) reactionmay be converted in to ivacaftor without isolating the Formula VIII oralternatively the compound of Formula VIII may be isolated as solid byknown methods.

The step c5) of the aforementioned process involves cyclization of thecompound of Formula VIII to obtain ivacaftor, when R₁ is hydrogen, or toobtain a compound of Formula IX, when R₁ is a protecting group anddeprotecting the Formula IX to obtain ivacaftor.

The cyclization of compound of Formula VIII is carried out in presenceof a suitable base to obtain a compound of Formula IX. The suitable baseincludes but is not limited to inorganic bases such as sodium hydroxide,potassium hydroxide, sodium methoxide, sodium ethoxide, sodiumtert-butoxide, potassium tert-butoxide, sodium carbonate, potassiumcarbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate,organic bases such as triethylamine, isopropylethylamine,diisopropylamine, diisopropylethylamine, N-methylmorpholine, piperidine,pyridine and the like and mixtures thereof; preferably potassiumcarbonate.

The cyclization of compound of Formula VIII is carried out in a suitablesolvent. The suitable solvent includes but is not limited to ethers,alcohols, aromatic hydrocarbons, amides, sulfoxides, nitriles andmixtures thereof. Preferably ethers include, but are not limited totetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl ether, methyltertiary butyl ether and the like; alcohols include, but are not limitedto methanol, ethanol, isopropanol and the like; aromatic hydrocarbonsinclude, but are not limited to toluene, xylene and the like; amidesinclude, but are not limited to dimethylformamide, dimethyl acetamide,N-methyl pyrrolidinone and the like; sulfoxides include, but are notlimited to dimethylsulfoxide, sulfolane and the like; nitriles include,but are not limited to acetonitrile, propionitrile and like and mixturesthereof; preferably dimethylformamide.

The deprotection of the compound of Formula IX is carried out inpresence of a suitable deprotecting agent and a suitable solvent.

The suitable deprotecting agent used herein for the deprotection of thecompound of Formula IX; wherein ‘R₁’ defined as above includes but isnot limited to acid deprotecting agent such as hydrochloric acid,hydrobromic acid, trifluoro acetic acid and the like and mixturethereof; base deprotecting agent such as potassium carbonate, sodiumhydroxide, sodium ethoxide and the like and mixture thereof; preferablypotassium carbonate.

The suitable solvent for deprotection of the compound of Formula IX;wherein ‘R₁’ defined as above includes but is not limited to alcohols,ketones, ethers, amides, sulfoxides and mixtures thereof. The alcoholsinclude, but are not limited to methanol, ethanol, isopropanol and thelike; ketones include, but are not limited to acetone, methyl isobutylketone, methyl ethyl ketone and the like; ethers include, but are notlimited to tetrahydrofuran, 2-methyl tetrahydrofuran, methyl tertiarybutyl ether and the like; amides include, but are not limited todimethyl formamide, dimethyl acetamide, N-methyl pyrrolidinone and thelike; sulfoxides include, but are not limited to dimethylsulfoxide,sulfolane and the like; and mixture thereof; preferablydimethylformamide.

The deprotection reaction may be carried out at a temperature of about0° C. to reflux temperature; preferably at 90° C. to about 110° C.

After completion of the deprotection reaction, the resultant ivacaftorof Formula I can be isolated by known isolation techniques, for examplethe resultant reaction mass may be adjusted pH to about 2.0 to 2.5 witha suitable acid such as hydrochloric acid, sulfuric acid, phosphoricacid, acetic acid and the like, followed by precipitated solid compoundcan be separated by filtration and the solid ivacaftor obtained may beoptionally purification from a suitable solvent such as methanol,ethanol and the like.

In another embodiment, the present invention provides a process for thepreparation of ivacaftor of Formula I or a pharmaceutically acceptablesalt thereof: comprising:

-   -   a6) reacting a compound of Formula VIb with (C₁₋₅        alkyl)₃-orthoformate to obtain a compound of Formula XIV,        wherein ‘R₂’ represents C₁₋₅ alkyl,

-   -   b6) reducing the compound of Formula XIV in presence of a        suitable reducing agent to obtain a compound of Formula XV, and

-   -   c6) cyclizing the compound of Formula XV in to ivacaftor.

The step a6) of the aforementioned process involves reaction of compoundof Formula VIb with (C₁₋₅ alkyl)₃-orthoformate to obtain a compound ofFormula XIV is same as the process described for the preparation ofcompound of Formula VIIa or Formula VIIb.

The step b6) of the aforementioned process involves reduction of thecompound of Formula XIV in presence of a suitable reducing agent toobtain a compound of Formula XV.

The suitable reducing agent used herein is selected from the groupconsisting of Fe/ammonium chloride, Fe/ammonium formate, Fe/HCl,hydrogen gas, Palladium on carbon, Raney nickel, Platinum oxide, Sodiumhydrosulfite, Zinc and the like; preferably Fe/ammonium chloride.

The reduction of the compound of Formula XIV is carried out in asuitable solvent. The suitable solvent includes but is not limited toethers, alcohols, amides, sulfoxides, water and mixtures thereof.Preferably ethers include, but are not limited to tetrahydrofuran,2-methyltetrahydrofuran, dimethyl ether, methyl tertiary butyl ether andthe like; alcohols include, but are not limited to methanol, ethanol,isopropanol and the like; amides include, but are not limited todimethylformamide, dimethylsulfoxide, dimethyl acetamide, N-methylpyrrolidinone and the like; sulfoxides include, but are not limited todimethylsulfoxide, sulfolane and the like; water and mixtures thereof;preferably ethanol.

The reduction of the compound of Formula XIV advantageously carried outat a temperature of about room temperature to reflux temperature;preferably at 60° C. to about 80° C.

The step c6) of the aforementioned process involves cyclization of thecompound of Formula XV in to ivacaftor.

In an embodiment, the process of step c6) of cyclization of the compoundof Formula XV in to ivacaftor is carried out without isolating thecompound of Formula XV.

In another embodiment, the present invention provides a process for thepreparation of ivacaftor of Formula I or a pharmaceutically acceptablesalt thereof; comprising:

-   -   a7) reacting a compound of Formula XVI with a compound of        Formula IVa or a salt thereof to obtain a compound of Formula        XVII,

-   -   b7) reacting the compound of Formula XVII with a compound of        Formula XVIII to obtain a compound of Formula XIII, and

-   -   c7) converting the compound of Formula XIII in to ivacaftor;        wherein ‘X’ represents halo or nitro; ‘R₁’ represents either        hydrogen or a suitable protecting group; ‘R₂’ represents C₁₋₅        alkyl; L and L′ represents a suitable leaving group.

The compound of Formula XVI or a salt thereof known in the art and canbe prepared by any process known in the art or by using the processdisclosed in applicant's PCT application No. 2016/075703 or by using theprocess disclosed in examples.

The step a7) of aforementioned process involves reaction of compound ofFormula XVI with a compound of Formula IVa or a salt thereof in presenceof a suitable base and in a suitable solvent to obtain a compound ofFormula XVII, wherein ‘R₂’ represents C₁₋₅ alkyl; L and L′ represents asuitable leaving group.

In a preferred embodiment the exemplary compound of Formula XVI, FormulaIVa and Formula XVII can be represented as follows:

Exemplary bases used herein for the reaction of a compound of FormulaXVI with a compound of Formula IVa or a salt thereof, includes but arenot limited to inorganic bases such as sodium hydroxide, potassiumhydroxide, sodium methoxide, sodium ethoxide, sodium tert-butoxide,potassium tert-butoxide, sodium carbonate, potassium carbonate, cesiumcarbonate, sodium bicarbonate, potassium bicarbonate, organic bases suchas triethylamine, isopropylethylamine, diisopropylamine,diisopropylethylamine, N-methylmorpholine, piperidine, pyridine and thelike and mixtures thereof; preferably pyridine.

The suitable solvent for the reaction of a compound of Formula XVI witha compound of Formula IVa or a salt thereof, include but is not limitedto amides, halogenated hydrocarbons, aromatic hydrocarbons and mixturesthereof. The amides include, but are not limited to dimethyl formamide,dimethyl acetamide, N-methyl pyrrolidinone and the like; halogenatedhydrocarbons include, but are not limited to methylene chloride,ethylene chloride and the like; aromatic hydrocarbons include, but arenot limited to toluene, xylene and the like and mixtures thereof;preferably methylene chloride.

The reaction of Formula XVI with a compound of Formula IVa or a saltthereof is advantageously carried out at a temperature of about roomtemperature to reflux temperature; preferably at 20° C. to about 40° C.

The step b7) of the aforementioned process involves reaction of thecompound of Formula XVII with a compound of Formula XVIII in presence ofa suitable base and in a suitable solvent to obtain a compound ofFormula XIII, wherein ‘R₁’, ‘R₂’, ‘X’, L and L′ are defined as above.

In a preferred embodiment the exemplary compound of Formula XVIII can berepresented as follows:

The base and solvent used herein for reaction of compound of FormulaXVII with a compound of Formula XVIII is same as used for the reactionof compound of Formula XVI with a compound of Formula IVa or a saltthereof as mentioned above.

The reaction of Formula XVII with a compound of Formula XVIII isadvantageously carried out at a temperature of about room temperature toreflux temperature; preferably at 40° C. to about 65° C.

The resultant compound of Formula XIII can be isolated by conventionalmethods; for example washing the reaction mass with a suitable aqueousbase such as sodium bicarbonate, potassium bicarbonate and the like.Then the product containing solvent may be separated and subjected toevaporation under vacuum to obtain solid compound as crude, which can beoptionally separated by adding suitable hydrocarbon solvent such ashexane, heptane, cyclohexane and the like; preferably heptane and thenfiltering the product.

The compound of Formula XIII obtained by the processes described just asabove can be used as intermediate in the preparation of ivacaftor of theinvention.

The step c7) of the aforementioned process involves convertion of thecompound of Formula XIII in to ivacaftor by the process same asdescribed above.

In another embodiment, the present invention provides a compound ofFormula XIII or a pharmaceutically acceptable salt thereof:

wherein ‘X’ represents Halo, —NO₂ or —NH₂, ‘R₁’ represents eitherhydrogen or a suitable protecting group; and ‘R₂’ represents C₁₋₅ alkyl;provided that wherein when “X” is —NO₂ or —NH₂ then ‘R₁’ is hydrogen.

In another embodiment, the present invention provides a compound ofFormula XIIIa or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula XIIIb or a pharmaceutically acceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula XIIIb, wherein ‘R₂’ represents C₁₋₅ alkyl, or a pharmaceuticallyacceptable salt thereof.

In another embodiment, the present invention provides a compound ofFormula XV, wherein ‘R₂’ represents C₁₋₅ alkyl, or a pharmaceuticallyacceptable salt thereof.

In another embodiment, the present invention provides ivacaftor or apharmaceutically acceptable salt thereof obtained by the processesdescribed herein, having a purity of at least about 97%, as measured byHPLC, preferably at least about 98% as measured by HPLC, and morepreferably at least about 99.5%, as measured by HPLC.

As used herein, the pharmaceutical acceptable salts include acidaddition salts formed with inorganic acids or with organic acids. Theinorganic acids may be selected from hydrochloric acid, hydrobromicacid, sulfuric acid, phosphoric acid, nitric acid, sulfamic acid, andthe like; organic acids may be selected from acetic acid, oxalic acid,fumaric acid, citric acid, succinic acid, tartaric acid, salicylic acid,benzoic acid, glycolic acid, methane sulfonic acid, ethanesulfonic acid,benzenesulfonic acid, p-toluenesulfonic acid, lactic acid, maleic acid,malonic acid, malic acid and the like.

In another embodiment, the present invention provides a pharmaceuticalcomposition, comprising ivacaftor or a pharmaceutically acceptable saltthereof prepared by the processes of the present invention and at leastone pharmaceutically acceptable excipient. Such pharmaceuticalcomposition may be administered to a mammalian patient in any dosageform, e.g., solid, liquid, powder, injectable solution, etc.

EXAMPLES

The following non limiting examples illustrate specific embodiments ofthe present invention. They are not intended to be limiting the scope ofthe present invention in any way.

Example-1: Preparation of Ivacaftor

4-oxo-1,4-dihydroquinoline-3-carboxylic acid (5 g), methylene chloride(100 ml) and triethylamine (5.35 g) were charged into a round bottomflask at 25-35° C. stirred at for 10 min at same temperature. Reactionsmass was cooled to 0-5° C., slowly add thionyl chloride (6.30 g) over aperiod of 15 min, then the reaction mass was heated to reflux andmaintained for 2 to 3 hrs. After completion of the reaction, reactionmass was distilled completely under vacuum at below 40° C. andco-distilled with methylene chloride (2×50 ml). Reaction mass was cooledto room temperature and diluted with methylene chloride (50 ml) furthercooled to 0-5° C. To the reaction mass was charged solution of5-amino-2,4-di-tert-butyl phenol hydrochloride (8.2 g) in methylenechloride (50 ml) and triethylamine (5.35 g) at 0-5° C. Reaction mass washeated to 25-35° C. and stirred for 4 to 6 hrs. After completion of thereaction, reaction mass was distilled completely under vacuum at below40° C. and to the resultant reaction ethyl acetate (100 ml) was chargedand washed with 5% sodium carbonate (2×50 ml), water (50 ml), 1% aq.HClsolution (50 ml) and water (50 ml) and the resultant organic layer wasdistilled completely u/v and co-distilled with ethanol to obtain crude.The obtaine crude was dissolved in ethanol (450 ml) at refluxtemperature and then distilled the resultant reaction mass upto ˜20 volat 40° C. Reaction mass was cooled to 25-35° C. then filtered the solidand washed with ethanol (10 ml). The resulting wet cake was dried undervacuum at 60-65° C. to obtain Ivacaftor. Yield: 5.0 g.

Example-2: Preparation ofN-(2,4-di-tert-butyl-5-hydroxyphenyl)-1-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide

N-Benzyl-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (3 g), methylenechloride (60 ml) and triethylamine (2.17 g) were charged in to a roundbottom flask at 25-35° C. and stirred for 10 min at same temperature.Reactions mass was cooled to 0-5° C., slowly add thionyl chloride (2.55g) over a period of 15 min, then the reaction mass was heated to refluxand maintained for 2 to 3 hrs. After completion of the reaction,reaction mass was distilled completely under vacuum at below 40° C. andco-distilled with methylene chloride (2×30 ml). Reaction mass was cooledto room temperature and diluted with methylene chloride (30 ml) furthercooled to 0-5° C. To the reaction mass was charged solution of5-amino-2,4-di-tert-butyl phenol hydrochloride (3.32 g) in methylenechloride (30 ml) and triethylamine (2.17 g) at 0-5° C. Reaction mass washeated to 25-35° C. and stirred for 4 to 6 hrs. After completion of thereaction, reaction mass was distilled completely under vacuum at below40° C. and to the resultant reaction ethyl acetate (60 ml) was chargedand washed with 5% sodium carbonate (2×30 ml), water (30 ml), 1% aq. HClsolution (30 ml) and water (30 ml) and the resultant organic layer wasdistilled completely u/v and co-distilled with ethanol to obtain crude.The obtained crude was dissolved in ethanol (270 ml) at refluxtemperature and then distilled the resultant reaction mass upto ˜20 volat 40° C. Reaction mass was cooled to 25-35° C. then filtered the solidand washed with ethanol (6 ml). The resulting wet cake was dried undervacuum at 60-65° C. to obtain title compound. Yield: 4.0 g.

Example-3: Preparation of Ivacaftor

N-(2,4-di-tert-butyl-5-hydroxyphenyl)-1-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide(3 g; obtained from Ex-2) and dimethylformamide (45 ml), 20% palladiumhydroxide (3 g) and ammonium formate (3 g) were charged into a roundbottom flask at 25-30° C. The reaction mass was heated to 70-80° C. andstirred for 3 hours. Then the reaction mass was cooled to 40° C. andfiltered. To the filtered mass water (180 ml) was added at 5-10° C.,then the reaction mass was stirred for 30 min at 25-30° C. and filteredthe precipitated solid and solid bed washed with water (15 ml). Theobtained wet cake was dissolved in ethyl acetate (90 ml) and filteredthrough celite bed and bed washed with ethyl acetate (10 ml). Filtratewas distilled completely u/v at below 50° C. and crude productco-distilled with ethanol (10 ml), charged ethanol (15 ml) to crudeproduct and stir for 30 min at 25-35° C. Filtered the obtained solidsand washed with ethanol (6 ml). Dry the material at 60-65° C. for 18 to24 hrs to obtain Ivacaftor. Yield: 2.0 g.

Example-4: Preparation of Compound of Formula Xia

2-fluorobenzoic acid (30 g), Meldrum acid (27.7 g),4-dimethylaminopyridine (39.2 g) and methylene chloride (300 ml) werecharged into a round bottom flask at 25-35° C. To the reaction mass wasadded pre dissolved solution of dicyclohexylcarbodiimide (57.6 g) inmethylene chloride (150 ml) over a period of 1 hr at 25-35° C. stirredat for 2-3 hr at same temperature. After completion of the reaction,charged 10% aq HCl (300 ml) and stirred for 15-20 min, separated theobtained salts from reaction mass by filtration and the resultantfilterate was washed with 10% HCl (150 ml) and water (150 ml). Organiclayer was distilled completely under vacuum at below 40° C. andco-distilled with diisopropylether (60 ml). The resultant reaction masswas treated with diisopropylether (150 ml) and stirred for 30 min.Filtered the obtained solids and washed with diisopropylether (60 ml).Dry the material at 40-55° C. to obtain title compound. Yield: 45.0 g;¹H NMR (CDCl₃): δ7.62 (d, 2H), δ7.3 (m, 1H), δ7.1 (m, 1H), δ5.2 (s, 1H),δ1.9 (s, 6H); ESI MS: 265 m/z (MH⁻).

Example-5: Preparation of Compound of Formula VIa

5-amino-2,4-di-tert-butyl phenol hydrochloride (7.7 g),diisopropylethylamine (3.9 g) and toluene (200 ml) were charged into around bottom flask at 25-35° C. Reactions mass was heated to 95-105° C.and was charged compound of Formula XIa (10 g) in lot wise and stirredfor 2-3 hr at reflux temperature. After completion of the reaction,reaction mass was distilled completely under vacuum at below 50° C. andco-distilled with heptane. The resultant reaction mass was stirred withheptane (50 ml) for 30 min. Filtered the obtained solids and dryed thematerial to obtain title compound. Yield: 12.0 g; ¹H NMR (CDCl₃): δ9.2(s, 1H), δ7.9 (m, 2H), δ7.54 (s, 1H), δ7.3 (m, 2H), δ7.1 (s, 1H), δ4.2(s, 2H), δ1.37 (s, 9H), δ1.34 (s,9H); ESI MS: 384 m/z (MH⁻).

Example-6: Preparation of Compound of Formula VIIa

Compound of Formula VIa (1 g) and toluene (10 ml) were charged into around bottom flask at 25-35° C. Reactions mass was heated to 60-65° C.and was charged dimethylformamide dimethyl acetal (1.2 g) and stirredfor overnight at same temperature. After completion of the reaction,distilled the reaction mass was completely under vacuum at below 50° C.to obtain crude compound. The obtained crude was purified by columnchromatography to obtain title compound. Yield: 1.0 g; ¹H NMR (CDCl₃):δ9.2 (s, 1H), δ7.9 (m, 2H), δ7.54 (s, 1H), δ7.3 (m, 2H), δ7.1 (s, 1H),δ3.9 (s, 1H), δ3.2 (s, 6H), δ1.37 (s, 9H), δ1.34 (s, 9H); ESI MS: 441m/z (MH⁺).

Example-7: Preparation of Compound of Formula XIIa

Compound of Formula XIa (10 g) and ethanol (50 ml) were charged into around bottom flask at 25-35° C. Reaction mass was heated to reflux andstirred for 2-3 hr at and temperature. After completion of the reaction,reaction mass was distilled completely under vacuum at below 50° C. andco-distilled with heptane. The resultant reaction mass was stirred withheptane (25 ml) for 30 min. Filtered the obtained solids and dryed thematerial to obtain title compound. Yield: 7.0 g; ¹H NMR (CDCl₃): δ8.0(m, 1H), δ7.6 (m, 1H), δ7.2 (m, 1H), δ7.1 (m, 1H), δ3.7 (m, 2H), δ3.6(s, 2H), δ1.1 (s, 3H); ESI MS: 211 m/z (MH⁺).

Example-8: Preparation of Compound of Formula VIa

5-amino-2,4-di-tert-butyl phenol hydrochloride (5.3 g),diisopropylethylamine (2.7 g) and toluene (100 ml) were charged into around bottom flask at 25-35° C. Reactions mass was heated to 95-105° C.and was charged compound of Formula XIIa (5 g) in lot wise and stirredfor 2-3 hr at reflux temperature. After completion of the reaction,reaction mass was distilled completely under vacuum at below 50° C. andco-distilled with heptane. The resultant reaction mass was stirred withheptane (25 ml) for 30 min. Filtered the obtained solids and dryed thematerial to obtain title compound. Yield: 7.0 g.

Example-9: Preparation of Ivacaftor

Compound of Formula VIIa (1 g; obtained from Ex-5), ethanol (10 ml) andammonium hydroxide (5 ml) were charged into a round bottom flask at25-35° C. and stirred for 1 hr at same temperature. After completion ofthe reaction, reaction mass was distilled completely under vacuum atbelow 50° C. and co-distilled with ethanol (10 ml) to obtain residue.The obtained residue was dissolved in dimethylformamide (5 ml) andcharged potassium carbonate (0.67 g) at 25-30° C. Reactions mass washeated to 85-95° C. and stirred for 2 hr at same temperature. Aftercompletion of the reaction, cooled the reaction mass to 25-30° C. andslowly added water (25 ml) over a period of 1 hr and stirred for 1 hr atsame temperature. Filtered the obtained solids and washed with water(2×10 ml) and dryed under vacuum. The obtained solids were dissolved inethyl acetate (10 ml) and washed with water (5 ml). Organic layer wasdistilled completely under vacuum and co-distilled with ethanol (10 ml)to obtain residue. The obtained residue was added ethanol (5 ml) at roomtemperature and the reaction mass was heated to 75-80° C. and stirredfor 1 hr. Reaction mass was cooled to 25-35° C. and filtered the solidsobtained and washed with ethanol (2 ml). Dry the material at 45-50° C.to obtain title compound. Yield: 0.55 g.

Example-10: Preparation of Compound of Formula VIIb

Compound of Formula VIIb was prepared from compound of formula VIbanalogously process according to Example-6.

Example-11: Preparation of Ivacaftor

Compound VIIb (1.0 g), iron powder (0.48 g) and ethanol (10.0 ml) werecharged into a round bottom flask at 25-35° C. and heated to 65° to 75°C. To the reaction mass was added ammonium chloride solution (1.14 gdissolved in water 5 ml) at 65 to 75° C. for 60 to 90 min and stirredfor 2 to 3 hr at same temperature. After the completion of the reaction,reaction mass was cooled to 25-35° C. and distilled reaction mass undervacuum at 50° C. to obtain a residue. To the obtained residue was addedethylacetate (10.0 ml) and water (10 ml) and stirred for 10 min andseparated the organic layer, washed the organic layer with water (10 ml)and distilled the reaction mass at 45 to 50° C. and co-distilled withethanol (10 ml) to obtain a residue. The obtained residue was addedethanol (5 ml) at room temperature and the reaction mass was heated to75-80° C. and stirred for 1 hr. Reaction mass was cooled to 25-35° C.and filtered the solids obtained and washed with ethanol (2 ml). Dry thematerial at 45-50° C. to obtain title compound. Yield: 0.7 g.

Example-11: Preparation of Compound of Formula XIIa

2-fluorobenzoic acid (10 g) toluene (80 ml) and dimethyl formamide (0.1ml) were charged into a round bottom flask at 25-35° C. To the reactionmass thionyl chloride (12.7 g) was added slowly over a period of 30 minat same temperature. Reaction mass was heated to reflux and stirred for3-4 hr. After completion of the reaction, reaction mass was cooled to55-65° C. and distilled completely under vacuum at 55-65° C. andco-distilled with toluene (2×20 ml) to obtain residue and the residuewas dissolved in tetrahydrofuran (50 ml). Tetrahydrofuran (150 ml) andmagnesium chloride (24.5 g) was added in another round bottom flask at25-35° C. Reaction mass was cooled to 10-15° C. and was added potassiumsalt of monoethylmalonate (36.4 g) at same temperature. To the reactionmass was added triethyl amine (21.6 g) slowly over a period of 30 minand reaction mass was heated to 25-35° C. and stirred for 8 hr at sametemperature. To the reaction mass was added above pre dissolvedtetrahydrofuran solution of 2-fluorobenzoyl chloride at 15-25° C. andstirred for 16 hr at 25-35° C. After completion of the reaction,reaction mass was distilled completely under vacuum at below 50° C. andcooled to 25-35° C. To the resultant reaction mass was added water (400ml) and stirred for 3 hr at same temperature. Filtered the precipitatedsolids and washed with water (10 ml). The obtained solids were stirredwith water (200 ml), and a mixture of water (100 ml) and sodiumbicarbonate (50 g), a mixture of water (100 ml) and hydrochloric acid(10 ml) sequentially at 25-35° C. and filtered the solid and washed withwater (10 ml). The obtained solid was stirred with methanol (20 ml) for40 min at 25-35° C. Filtered the solids and washed with methanol (10 ml)and dryed the material to obtain title compound. Yield: 13.5 g.

Example-12: Preparation of Compound of Formula VIp′

5-Amino-2,4-di-tert-butylphenylmethyl carbonate (5 g), compound ofFormula XIa (6.19 g; obtained from Ex-4) and ethyl acetate (50 mL) werecharged in to round bottom flask at 25-35° C. and stirred for 2 hrs atsame temperature. Reaction mass was heated to 40° C. and stirred for 2hrs at same temperature and was further heated to 60° C. and stirred for2 hrs. After completion of reaction, reaction mass was distilled outcompletely under vacuum at 50° C. and co-distilled with n-Heptane(2×20.0 mL). To the resultant reaction mass was charged n-heptane (30mL) at 25-35° C. and stirred for 60 min. filtered the obtained solidsand dried the material at 40-45° C. to get title compound of2,4-di-tert-butyl-5-(3-(2-fluorophenyl)-3-oxopropanamido) phenyl methylcarbonate of Formula VIp. Yield: 7.9 g; ¹H NMR (CDCl₃): δ9.2 (brs, 1H),δ7.9 (d, 2H), δ7.65 (t, 1H), δ7.5 (s, 1H), δ7.4 (s, 1H), δ7.2 (t, 1H),δ4.2 (s, 2H), δ3.90 (S, 3H), δ1.37 (s, 9H), δ1.34 (s, 9H); ESI MS 442m/z (M⁻H).

Example-13: Preparation of Compound of Formula XIIIp

Compound of Formula VIp′ (6 g; obtained from Ex-12), acetic anhydride(8.95 mL), triethylorthoformate (15.75 mL) and zinc chloride (0.16 g)were charged in to round bottom flask at 25-35° C. and stirred for 6 hrsat same temperature. After completion of reaction, reaction mass wasquenched with water (30 mL) and compound was extracted with ethylacetate (60 mL). Resultant organic layer was washed with water (30 mL)and distilled completely under vacuum at below 50° C. to get titlecompound of Formula XIIIp. Yield: 6.75 g; ¹HNMR (300 MHz, CDCl₃): δ10.23(brs, 1H), δ9.3 (d, 1H), δ8.5 (s, 1H), δ7.69 (t, 1H), δ7.56 (t, J=7.5Hz, 1H), δ7.48 (d, 1H), δ7.38 (s, 1H), δ7.25 (s, 1H), δ3.89 (s, 3H),δ2.30 (s, 2H), δ1.37 (s, 9H), δ1.33 (s, 9H); ESI MS−500 m/z (M+1).

Example-14: Preparation of Ivacaftor

Compound of Formula XIIIp (6.75 g), ethanol (70 mL) and ammoniumhydroxide (35 mL) were charged in to round bottom flask at 25-35° C.Reaction mass was heated to reflux and stirred for 10 to 12 hrs at sametemperature. After completion of reaction, reaction mass was distilledat 45-50° C. under vacuum and co-distilled with ethanol (10 mL) toobtain a residue. The obtained residue was dissolved indimethylformamide (54 mL) and charged potassium carbonate (5.94 g) at25-30° C. Reactions mass was heated to 100-105° C. and stirred for 12hrs at same temperature. After completion of the reaction, cooled thereaction mass to 25-30° C. and slowly added water (270 mL) and pH of thereaction mass was adjusted to 2.0 with aq hydrochloric acid. Filteredthe precipitated solids and was charged ethanol (200 mL) and heated to75-80° C. and stirred for a period of 60 min at same temperature.Reaction mass was cooled to 25-35° C. and distilled reaction mass to 60mL. Filtered the solids obtained and washed with ethanol (12 ml). Drythe material at 45-50° C. to obtain title compound. Yield: 5.0 g.

Example-15: Preparation of (E)-3-ethoxyacryloyl chloride of Formula XVIa

To a 250 ml round bottom flask ethyl vinyl ether (25 g) was added dropwise to oxalyl chloride (66 g) at 0° C. The mixture was allowed to warmto room temperature and stirred for 12 hrs at same temperature. Aftercompletion of the reaction, oxalyl chloride was distilled off and theresidue heated to 120° C. for 30 min. Then the resultant crude residuewas purified by vacuum distillation to yield (E)-3-ethoxyacryloylchloride of Formula XVIa. Yield: 23.8 g; ¹H-NMR (CDCl₃): δ7.78 (1H, d),δ5.51 (1H, d), δ4.05 (2H, q), δ1.40 (3H, t); B.P: 85-87° C.

Example-16: Preparation of Compound of Formula IVp

2,4-di-tert-butyl-5-nitro phenol (30 g), N,N-dimethylamino pyridine(0.73 g), triethylamine (24.16 g) and methylene chloride (120 mL) werecharged in to round bottom flask at 25-35° C. Reaction mass was cooledto 0-5° C., methyl chloro formate (16.92 g) was slowly added over aperiod of 60 min and reaction mass was heated to 25-30° C. Aftercompletion of the reaction, filtered the reaction mass and washed withethyl acetate (150 mL). Combined organic layer distilled completelyunder vacuum at below 40° C. Then the resultant crude mass was dissolvedin to ethyl acetate (3000 mL) and washed with water (150 mL) and 5%aqueous hydrochloride solution (150 mL) and followed by water (150 mL).Organic layer was distilled completely to get 2,4-di tert-butyl-5-nitrophenyl methyl carbonate (36.6 g). To the obtained2,4-di-tert-butyl-5-nitro phenyl methyl carbonate (22.5 g) was addedaqueous ammonium chloride (38.90 g), ethanol (225), Iron (16.23 g) atroom temperature and heated to reflux for 3 hrs. After completion of thereaction, temperature was cooled to 30° C. and filtered through celite.The celite was washed with ethanol and combined filtrates were distilledcompletely under vacuum at below 50° C. To the obtained reaction masswater (112 mL) was added at 25-35° C. and stirred for 30 min andfiltered the precipitated solid and washed with water (60 mL) to get5-amino-2,4-di-tert-butyl phenyl methyl carbonate of Formula IVp as awhite solid (18.75 g).

Example-17: Preparation of Compound of Formula XVIIa

5-Amino 2,4-di-tert-butyl phenyl methyl carbonate (7 g), methylenechloride (70 mL), pyridine (4.95 g) were charged in to round bottomflask at 25-35° C. and stirred for 15 min at same temperature. Reactionmass was cooled to 0-5° C., methylene chloride (35 mL) solution of(E)-3-ethoxyacryloyl chloride of Formula XVIa (3.71 g) was added slowlyover a period of 20-30 min. Reaction mass temperature was raised to25-35° C. and stirred for 5 hrs. After completion of the reaction,reaction mass was washed with water (70 mL), 5% sodium bicarbonate (70mL) and followed by water (70 mL) sequentially. Organic layer wasdistilled completely under vacuum and the resultant crude product waspurified by column purification using ethyl acetate/hexane to get titlecompound as a cream coloured solid. Yield: 8 g; ¹H-NMR (CDCl₃); δ7.6 (d,1H) δ7.46 (s, 1H), δ7.26 (s, 1H), δ6.83 (brd, 1H), δ3.96 (q, 2H), δ3.89(s, 3H), δ 1.4 (d, 3H), δ1.25 (s, 9H), δ1.24 (s, 9H); ESI MS: 378 m/z(MH⁺).

Example-18: Preparation of Compound of Formula XIIIa

[(E)-3-ethoxyprop-2-enoyl]-5-amino-2,4-di-tert-butyl phenyl methylcarbonate of Formula XVIIa (0.5 g), triethylamine (0.4 mL) and toluene(5 mL) were charged in to round bottom flask at 25-35° C. Reaction masswas heated to 50-55° C. and slowly added 2-fluoro benzoyl chloride (0.35g in toluene 2.5 mL) over a period of 10 min and stirred for 5 hrs atsame temperature. After completion of the reaction, reaction mass wascooled to 25-35° C. and washed with water and followed by sodiumbicarbonate. Organic layer was distilled completely under vacuum atbelow 50° C. and co-distilled with heptane. To the resultant reactionmass heptane (5 mL) was added and stir for 30 min. Filtered the obtainedsolid to get2,4-di-tert-butyl-5-(3-ethoxy)-2-(2-fluorobenzoyl)acrylamido)phenylmethyl carbonate of Formula XIIIa as a cream color solid. Yield: 0.66 g;¹H-NMR (CDCl₃): δ10.23 (brs, 1H), δ9.3 (d, 1H), δ8.5 (s, 1H), δ7.69 (t,1H), δ7.56 (t, 1H), δ7.48 (d, 1H), δ7.38 (s, 1H), δ7.25 (s, 1H), δ3.89(s, 3H), δ2.30 (s, 2H), δ1.37 (s, 9H), δ1.33 (s, 9H); Mass (M+1)−500.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore the above description should notbe constructed as limiting, but merely as exemplifications of preferredembodiments. For example, the functions described above and implementedas the best mode for operating the present invention are forillustration purposes only. Other arrangements and methods may beimplemented by those skilled in the art without departing from the scopeand spirit of this invention. Moreover, those skilled in the art willenvision other modifications within the scope and spirit of thespecification appended hereto.

We claim:
 1. A process for preparation of ivacaftor of Formula I or a pharmaceutically acceptable salt thereof,

comprising: a) reacting a compound of Formula III with a compound of Formula IV or a salt thereof to obtain a compound of Formula V,

and b) optionally deprotecting the compound of Formula V in a deprotecting agent in a solvent to obtain the ivacaftor of Formula I, wherein ‘R’ represents hydrogen or a cleavable group and ‘X’ represents a leaving group.
 2. The process of claim 1, wherein the cleavable group is selected from the group consisting of tertiary butyloxy carbonyl, carboxy benzoyl, fluorenylmethyloxycarbonyl, allyloxycarbonyl, a methyl carbamate, an ethyl carbamate, phthalimide, formyl, acetyl, pivaloyl, trityl, benzyl, benzoyl, p-nitrobenzoyl, p-phenyl benzyl, 4-methoxy benzyl, 4-trifluoromethyl benzyl, 4-chloro benzyl, trimethylsilyl, tert-butyldiphenylsilyl, tert-butyldimethylsilyl, and triisopropylsilyl.
 3. The process of claim 1, wherein the leaving group is selected from the group consisting of chloro, bromo, iodo, mesyl, tosyl, triflate and nosyl.
 4. The process of claim 1, wherein ‘R’ represents hydrogen or benzyl and ‘X’ is chloro.
 5. The process of claim 1, wherein the step a) is carried out in presence of a base and a solvent.
 6. The process of claim 5, wherein the solvent is selected from the group consisting of tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl ether, diisopropyl ether, methyl tertiary butyl ether, 1,4-dioxane, methylene chloride, ethylene chloride, chloroform, toluene, xylene, dimethylformamide, dimethyl acetamide, N-methyl pyrrolidinone, dimethylsulfoxide, sulfolane, acetonitrile, propionitrile, and mixtures thereof.
 7. The process of claim 5, wherein the base is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, sodium-tert-butoxide, potassium-tert-butoxide, sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, potassium bicarbonate, triethylamine, isopropylethylamine, diisopropyl amine, diisopropyl ethylamine, N-methyl morpholine, piperidine, pyridine, and mixtures thereof.
 8. The process of claim 5, wherein the solvent is one of methylene chloride, tetrahydrofuran, and dimethylformamide, and the base is one of triethylamine, diisopropyl ethylamine, and potassium hydroxide.
 9. The process of claim 1, wherein the deprotecting agent is selected from the group consisting of palladium on carbon, palladium hydroxide, raney nickel, platinum oxide, cericammoniumnitrate, and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
 10. The process of claim 1, wherein the deprotection is carried out with palladium hydroxide in presence of a hydrogen source.
 11. The process of claim 1, wherein the solvent of step b) is selected from the group consisting of methanol, ethanol, isopropanol, acetone, methyl isobutyl ketone, methyl ethyl ketone, acetonitrile, propionitrile, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethyl ether, diisopropyl ether, methyl tertiary butyl ether, 1,4-dioxane, dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidinone, and mixtures thereof.
 12. The process of claim 1, wherein the deprotection is carried out with palladium hydroxide and ammonium formate in dimethyl formamide.
 13. The process of claim 1, further comprising: c) combining the ivacaftor of Formula I or the pharmaceutically acceptable salt thereof with at least one pharmaceutically acceptable excipient. 